David Cameron has denounced the ban as "ridiculous", and all the main Churches in Northern Ireland have criticised it.

DCM, which handles adverts for Odeon, Cineworld and Vue cinemas, released a new statement amid threats from the Church of England (CoE) of legal action over the ban.

The advert, by JustPray.uk, shows the Lord's Prayer being recited by members of the public and also features Archbishop of Canterbury Justin Welby.

The minute-long advert received clearance from the British Board of Film Classification and the Cinema Advertising Authority, but DCM has refused to show it in cinemas.

A DCM statement said: "While there has been passionate debate about this issue, we know many customers support our policy. We believe a clear neutral stance remains the fairest policy for all and allows DCM to treat all political and religious beliefs equally."

The CoE initially believed the ad had been approved, but was later told that due to a DCM policy not to run adverts which could potentially cause offence, the film would not be shown.